Cancer treatments include extirpation of cancer by surgical operation, radiotherapy, treatment with anti-cancer medication, and immunotherapy. Among these treatments, immunotherapy in particular has drawn attention in recent years because it is a treatment more selective and specific against cancer with least side effects. Inter alia, attempts have been extensively made to treat cancer and leukemia by targeting WT1 protein, which is abundantly present in many types of cancer cells and leukemia cells. In order to study the mechanism of the WT1-targeted anti-cancer therapy and to further increase the effect of the therapy, it is necessary to identify the nucleotide sequences of the T-cell receptor (TCR) genes of WT1-specific cytotoxic T-cells (CTL) and the amino acid sequences of the receptor peptides encoded by the nucleotide sequences. However, up to the present date, little is known about the sequences of those receptor genes and the receptor peptides, let alone that no effective use of them has been described, although a number of researches have been conducted (see, e.g., non-patent documents 1-5).    Non-Patent Document 1: Vα lmori D. et al., J. Immunol. 168: 4231-4240, 2002    Non-Patent Document 2: Dietrich P Y. et al., Cancer Res. 61: 2047-2054, 2001    Non-Patent Document 3: Coulie P G. et al., Proc. Natl. Acad. Sci. U.S.A. 98: 10290-10295, 2001    Non-Patent Document 4: Godelaine D. et al. J. Immunol. 171: 4893-4897, 2003    Non-Patent Document 5: Mandruzzato S. et al., J. Immunol. 169: 4017-4024, 2002